The effect of tooth wear on the feeding behaviour of free‐ranging koalas (<i>Phascolarctos cinereus</i>, Goldfuss)

Logan, Murray; Sanson, Gordon Drummond

doi:10.1017/s0952836902000080

Cited by 58 publications

(47 citation statements)

References 32 publications

(54 reference statements)

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“…Dental wear, the loss of tooth tissue, threatens the survival of individual mammals in the wild by jeopardizing their rate of food acquisition and processing [1][2][3]. Studied intensively for 60 years [4], wear patterns reflect the diet of living mammals and are capable of predicting diet in extinct forms [5 -8].…”

Section: Introductionmentioning

confidence: 99%

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

Lucas

Omar

Al‐Fadhalah

et al. 2013

J. R. Soc. Interface.

241

303

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The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss.

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Section: Introductionmentioning

confidence: 99%

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

Lucas

Omar

Al‐Fadhalah

et al. 2013

J. R. Soc. Interface.

241

303

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“…The loss of occlusal biting surfaces reduces fine particulate production but the koala compensates by increasing intake and developing merycism behaviour Sanson, 1986a, Logan andSanson, 2002).…”

Section: 2mentioning

confidence: 99%

Oral health in South East Queensland Koalas: Prevalence of periodontal disease and other pathologies

Pettett¹

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The koala (Phascolarctos cinereus) is one of Australia's most highly specialised folivores with a diet exclusively of eucalyptus leaves to provide all nutritive needs. For this it is dependent on good dentition for optimal health and quality of life. The purpose of this study was to characterise and describe the level of oral health and disease in koalas and then create tools for ongoing analysis.The historical records over a 17-year period were noted for the koalas admitted to the Moggill Koala Hospital in South East Queensland. Further, in this study the conclusions were that oral health issues when they existed were only being identified as "low key" due to the lack of investigative tools being used during examinations. This provided the reasoning and impetus behind developing tools to determine the true extent of oral health conditions in the koala. A suitable assessment tool for diagnosing the oral health was designed based on the index scoring methodology and the layout of the Moggill Koala Hospital admission chart, a new oral health chart template was developed. The chart was based on examination of 30 "free-range koalas" and validation and quality assurance analysis of four examiners of varying qualifications. The chart was separated into three sections; containing general animal information such as sex, age, and current systemic health; the General Oral Cavity section and containing information on 12 koala-specific health questions and finally a section on the periodontal health. The charting data is multifunctional with analysis of individual koalas, (sex, group or age). The data from each section provided an index value that was compatible with values from other species clinical charting systems.Using the chart, populations of 200 "free-range" and 95 captive koalas (from three zoos) were examined. Three major indexes were developed during the chart development process and used the following equation; General Oral Cavity (GOCI) + Oral Health Index (OHI) = Final Oral Health Index (FOHI). Initially, the three major index values plus all additional information of each chart were analysed to show the current baseline values of oral health conditions in the koala. Any ii comparison based on singular or multiple animals would either show a decline, same rate or increase from the baseline. These baseline parameters could be compared against any other species that uses the same 0-3 index system.The proportion of koalas from the whole population with an orally related problem was 86%.The average FOHI for the koala as a species was 3.78 ± 3.19, median 3.00. This is the mild category and held 84.5% of all cases. The maximum scores for the groups showed Zoo 3 as having lower range (Zoo 1; 11.42 for a TWC 1 male, Zoo 2; 13.40, Zoo 3; 4.13 and "free-range"; 15.98). The third zoo was the only group to have also had significantly better oral health than "free-range" koalas.Captive koalas showed high scoring at young age (11.42), the "free-range" comparable age score was 3.84. At population level when controlli...

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“…Loss of tooth tissue is vital to avoid because the teeth of most mammals grow for a limited period and are not replaced in adults [2][3][4]. Circumstantial evidence from several mammalian species strongly suggests that the loss of critical features on the working surfaces of the teeth is deleterious to tooth function and to the overall health and survival of afflicted individuals [5][6][7][8][9][10]. It is thus logical to suppose that natural selection has acted to minimize threats to the integrity of the working surface of a tooth.…”

Section: Introductionmentioning

confidence: 99%

Dental abrasion as a cutting process

Lucas

Wagner²,

Al‐Fadhalah

et al. 2016

Interface Focus.

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A mammalian tooth is abraded when a sliding contact between a particle and the tooth surface leads to an immediate loss of tooth tissue. Over time, these contacts can lead to wear serious enough to impair the oral processing of food. Both anatomical and physiological mechanisms have evolved in mammals to try to prevent wear, indicating its evolutionary importance, but it is still an established survival threat. Here we consider that many wear marks result from a cutting action whereby the contacting tip(s) of such wear particles acts akin to a tool tip. Recent theoretical developments show that it is possible to estimate the toughness of abraded materials via cutting tests. Here, we report experiments intended to establish the wear resistance of enamel in terms of its toughness and how friction varies. Imaging via atomic force microscopy (AFM) was used to assess the damage involved. Damage ranged from pure plastic deformation to fracture with and without lateral microcracks. Grooves cut with a Berkovich diamond were the most consistent, suggesting that the toughness of enamel in cutting is 244 J m 22, which is very high. Friction was higher in the presence of a polyphenolic compound, indicating that this could increase wear potential.

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The effect of tooth wear on the feeding behaviour of free‐ranging koalas (Phascolarctos cinereus, Goldfuss)

Cited by 58 publications

References 32 publications

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

Oral health in South East Queensland Koalas: Prevalence of periodontal disease and other pathologies

Dental abrasion as a cutting process

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